If your model contains an invalid frame connection, Simscape™ Multibody™ issues an error and the model does not simulate. Possible error sources include:
Rigidity loops — Rigidly connecting multiple frames in a closed loop
Shorted Rigid Transform Blocks — Rigidly connecting base and follower frame ports of a Rigid Transform block
A rigidity loop is a closed loop of Rigid Transform blocks. The loop contains one redundant Rigid Transform block that over-constrains the subsystem. If a rigidity loop is present, Simscape Multibody issues an error and the model does not simulate.
To remove the simulation error, disconnect one Rigid Transform block. This step removes the redundant constraint, and allows the model to simulate. The following figure shows a rigidity loop. The loop contains four Rigid Transform blocks directly connected to each other.
A shorted Rigid Transform block contains a direct connection line between base (B) and follower frames (F). The connection line makes the two port frames coincident in space. However, the Rigid Transform block enforces a spatial transformation that translates or rotates one port frame relative to the other. The result is a conflict in the frame definition.
If a shorted Rigid Transform block is present, Simscape Multibody issues an error and the model does not simulate. The error remains even if the Rigid Transform block specifies no rotation and no translation. To remove the simulation error, delete the direct connection line between base and follower frame ports of the Rigid Transform block. The following figure shows a shorted Rigid Transform block.